"""Support for Modbus switches."""
from __future__ import annotations

from abc import ABC
import logging
from typing import Any

from pymodbus.exceptions import ConnectionException, ModbusException
from pymodbus.pdu import ExceptionResponse
import voluptuous as vol

from homeassistant.components.switch import PLATFORM_SCHEMA, SwitchEntity
from homeassistant.const import (
    CONF_COMMAND_OFF,
    CONF_COMMAND_ON,
    CONF_NAME,
    CONF_SLAVE,
    STATE_ON,
)
from homeassistant.helpers import config_validation as cv
from homeassistant.helpers.entity import ToggleEntity
from homeassistant.helpers.restore_state import RestoreEntity
from homeassistant.helpers.typing import ConfigType, HomeAssistantType

from .const import (
    CALL_TYPE_COIL,
    CALL_TYPE_REGISTER_HOLDING,
    CALL_TYPE_REGISTER_INPUT,
    CONF_COILS,
    CONF_HUB,
    CONF_REGISTER,
    CONF_REGISTER_TYPE,
    CONF_REGISTERS,
    CONF_STATE_OFF,
    CONF_STATE_ON,
    CONF_VERIFY_REGISTER,
    CONF_VERIFY_STATE,
    DEFAULT_HUB,
    MODBUS_DOMAIN,
)
from .modbus import ModbusHub

_LOGGER = logging.getLogger(__name__)


REGISTERS_SCHEMA = vol.Schema(
    {
        vol.Required(CONF_COMMAND_OFF): cv.positive_int,
        vol.Required(CONF_COMMAND_ON): cv.positive_int,
        vol.Required(CONF_NAME): cv.string,
        vol.Required(CONF_REGISTER): cv.positive_int,
        vol.Optional(CONF_HUB, default=DEFAULT_HUB): cv.string,
        vol.Optional(CONF_REGISTER_TYPE, default=CALL_TYPE_REGISTER_HOLDING): vol.In(
            [CALL_TYPE_REGISTER_HOLDING, CALL_TYPE_REGISTER_INPUT]
        ),
        vol.Optional(CONF_SLAVE): cv.positive_int,
        vol.Optional(CONF_STATE_OFF): cv.positive_int,
        vol.Optional(CONF_STATE_ON): cv.positive_int,
        vol.Optional(CONF_VERIFY_REGISTER): cv.positive_int,
        vol.Optional(CONF_VERIFY_STATE, default=True): cv.boolean,
    }
)

COILS_SCHEMA = vol.Schema(
    {
        vol.Required(CALL_TYPE_COIL): cv.positive_int,
        vol.Required(CONF_NAME): cv.string,
        vol.Required(CONF_SLAVE): cv.positive_int,
        vol.Optional(CONF_HUB, default=DEFAULT_HUB): cv.string,
    }
)

PLATFORM_SCHEMA = vol.All(
    cv.has_at_least_one_key(CONF_COILS, CONF_REGISTERS),
    PLATFORM_SCHEMA.extend(
        {
            vol.Optional(CONF_COILS): [COILS_SCHEMA],
            vol.Optional(CONF_REGISTERS): [REGISTERS_SCHEMA],
        }
    ),
)


async def async_setup_platform(
    hass: HomeAssistantType, config: ConfigType, async_add_entities, discovery_info=None
):
    """Read configuration and create Modbus switches."""
    switches = []
    if CONF_COILS in config:
        for coil in config[CONF_COILS]:
            hub: ModbusHub = hass.data[MODBUS_DOMAIN][coil[CONF_HUB]]
            switches.append(ModbusCoilSwitch(hub, coil))
    if CONF_REGISTERS in config:
        for register in config[CONF_REGISTERS]:
            hub: ModbusHub = hass.data[MODBUS_DOMAIN][register[CONF_HUB]]
            switches.append(ModbusRegisterSwitch(hub, register))

    async_add_entities(switches)


class ModbusBaseSwitch(ToggleEntity, RestoreEntity, ABC):
    """Base class representing a Modbus switch."""

    def __init__(self, hub: ModbusHub, config: dict[str, Any]):
        """Initialize the switch."""
        self._hub: ModbusHub = hub
        self._name = config[CONF_NAME]
        self._slave = config.get(CONF_SLAVE)
        self._is_on = None
        self._available = True

    async def async_added_to_hass(self):
        """Handle entity which will be added."""
        state = await self.async_get_last_state()
        if not state:
            return
        self._is_on = state.state == STATE_ON

    @property
    def is_on(self):
        """Return true if switch is on."""
        return self._is_on

    @property
    def name(self):
        """Return the name of the switch."""
        return self._name

    @property
    def available(self) -> bool:
        """Return True if entity is available."""
        return self._available


class ModbusCoilSwitch(ModbusBaseSwitch, SwitchEntity):
    """Representation of a Modbus coil switch."""

    def __init__(self, hub: ModbusHub, config: dict[str, Any]):
        """Initialize the coil switch."""
        super().__init__(hub, config)
        self._coil = config[CALL_TYPE_COIL]

    def turn_on(self, **kwargs):
        """Set switch on."""
        self._write_coil(self._coil, True)
        self._is_on = True

    def turn_off(self, **kwargs):
        """Set switch off."""
        self._write_coil(self._coil, False)
        self._is_on = False

    def update(self):
        """Update the state of the switch."""
        self._is_on = self._read_coil(self._coil)

    def _read_coil(self, coil) -> bool:
        """Read coil using the Modbus hub slave."""
        try:
            result = self._hub.read_coils(self._slave, coil, 1)
        except ConnectionException:
            self._available = False
            return False

        if isinstance(result, (ModbusException, ExceptionResponse)):
            self._available = False
            return False

        self._available = True
        # bits[0] select the lowest bit in result,
        # is_on for a binary_sensor is true if the bit is 1
        # The other bits are not considered.
        return bool(result.bits[0] & 1)

    def _write_coil(self, coil, value):
        """Write coil using the Modbus hub slave."""
        try:
            self._hub.write_coil(self._slave, coil, value)
        except ConnectionException:
            self._available = False
            return

        self._available = True


class ModbusRegisterSwitch(ModbusBaseSwitch, SwitchEntity):
    """Representation of a Modbus register switch."""

    def __init__(self, hub: ModbusHub, config: dict[str, Any]):
        """Initialize the register switch."""
        super().__init__(hub, config)
        self._register = config[CONF_REGISTER]
        self._command_on = config[CONF_COMMAND_ON]
        self._command_off = config[CONF_COMMAND_OFF]
        self._state_on = config.get(CONF_STATE_ON, self._command_on)
        self._state_off = config.get(CONF_STATE_OFF, self._command_off)
        self._verify_state = config[CONF_VERIFY_STATE]
        self._verify_register = config.get(CONF_VERIFY_REGISTER, self._register)
        self._register_type = config[CONF_REGISTER_TYPE]
        self._available = True
        self._is_on = None

    def turn_on(self, **kwargs):
        """Set switch on."""
        # Only holding register is writable
        if self._register_type == CALL_TYPE_REGISTER_HOLDING:
            self._write_register(self._command_on)
            if not self._verify_state:
                self._is_on = True

    def turn_off(self, **kwargs):
        """Set switch off."""
        # Only holding register is writable
        if self._register_type == CALL_TYPE_REGISTER_HOLDING:
            self._write_register(self._command_off)
            if not self._verify_state:
                self._is_on = False

    @property
    def available(self) -> bool:
        """Return True if entity is available."""
        return self._available

    def update(self):
        """Update the state of the switch."""
        if not self._verify_state:
            return

        value = self._read_register()
        if value == self._state_on:
            self._is_on = True
        elif value == self._state_off:
            self._is_on = False
        elif value is not None:
            _LOGGER.error(
                "Unexpected response from hub %s, slave %s register %s, got 0x%2x",
                self._hub.name,
                self._slave,
                self._register,
                value,
            )

    def _read_register(self) -> int | None:
        try:
            if self._register_type == CALL_TYPE_REGISTER_INPUT:
                result = self._hub.read_input_registers(
                    self._slave, self._verify_register, 1
                )
            else:
                result = self._hub.read_holding_registers(
                    self._slave, self._verify_register, 1
                )
        except ConnectionException:
            self._available = False
            return

        if isinstance(result, (ModbusException, ExceptionResponse)):
            self._available = False
            return

        self._available = True

        return int(result.registers[0])

    def _write_register(self, value):
        """Write holding register using the Modbus hub slave."""
        try:
            self._hub.write_register(self._slave, self._register, value)
        except ConnectionException:
            self._available = False
            return

        self._available = True